Infection control is a major concern for health care professionals. Viruses and bacteria on contaminated hands are easily spread among people in health care facilities such as hospitals. Of course, the risk of infection is also present in public places other than hospitals, such as in gyms, washrooms, restaurants, and schools.
Washing hands with detergents or soaps is a way to reduce the risk of infection. However, in certain environments, such as hospitals, the level of disinfection required cannot be achieved by most common products. Consequently, hand disinfectants have been developed to achieve higher levels of disinfection where the need exists. These types of products generally contain alcohols, iodines/iodophors, chlorhexidine gluconate (CHG), phenolic compounds, quaternary ammonium compounds or combinations thereof.
A problem with existing products is that they often sacrifice disinfectant activity for the sake of skin mildness or vice versa. For example, while raising the concentration of the active ingredient may lead to a higher level of disinfection, such higher concentration frequently leads to increased skin irritation.
As well, many common disinfecting ingredients have inherent disadvantages. For example, while alcohols are effective in providing rapid rates of disinfection, they are flammable and therefore give rise to safety risks in use and storage. As defatting agents, they can cause dry, chapped or cracked skin on repeated use. Furthermore, their anti-microbial activity is dependent on concentration and tends to drop dramatically when used on wet hands resulting in insufficient germ kill. To overcome some of these disadvantages, it is known to include additional ingredients such as emollients, humectants, and surfactants. For example, U.S. Pat. No. 6,617,294 to Narula et al. issued Sep. 9, 2003 discloses a waterless disinfecting hand cleanser made of a combination of 60 to 90% w/w of an alcohol, silicone based materials, and humectants.
Parachlorometaxylenol (PCMX) and triclosan are common phenolic compounds used in antiseptic hand wash solutions. See, for example, European patent 505,935 B1, assigned to Becton, Dickinson and Company and granted on Feb. 4, 1998, which discloses an anti-microbial skin formulation containing PCMX, a block copolymer, and a lauryl sulfosuccinate. Although PCMX and triclosan have lower toxicity than other phenols, and are rather mild to the skin, their germicidal activity is low and depends on the formulation ingredients.
Iodine and iodophors have been used in antiseptic hand wash formulations for a long time. Their germicidal activities are low and reduced in the presence of organic matter. Furthermore, these ingredients are toxic and can irritate and stain skin.
Chlorhexidine gluconate (CHG) is used as a skin cleanser, pre-surgical scrub, germicidal hand rinse, and wound cleaner. It is less effective against gram-negative bacteria as compared to gram-positive bacteria and exhibits relatively low germicidal activity.
Hydrogen peroxide is a broad-spectrum germicide effective against bacteria, yeast, fungi, viruses and spores. It is non-toxic and its breakdown products, oxygen and water, are innocuous thus making it safe to the environment. At low concentrations (e.g. 3% w/w), it is non-irritating to skin, but exhibits low germicidal activity. For example, a solution containing 3% w/w hydrogen peroxide takes 20 minutes to achieve a greater than 6 log reduction in Staphylococcus aureus, which is too long for many applications. Increasing the concentration of hydrogen peroxide will increase the rate of disinfection. For example, a 25% w/w aqueous solution of hydrogen peroxide requires only 20 seconds to achieve a greater than 6 log reduction in Staphylococcus aureus. However, the solution is corrosive at this concentration and requires special handling procedures.
While skin disinfecting formulations exist, there is still a need for new formulations that are both safe and capable of achieving an effective rate of disinfection at realistic contact times. The present invention is intended to meet this need.